U.S. patent number 5,904,631 [Application Number 08/825,615] was granted by the patent office on 1999-05-18 for dual electric motor drive with planetary gearing.
This patent grant is currently assigned to Toyota Jidosha Kabushiki Kaisha. Invention is credited to Hideaki Matsui, Kunio Morisawa, Shuji Nagano, Yutaka Taga.
United States Patent |
5,904,631 |
Morisawa , et al. |
May 18, 1999 |
Dual electric motor drive with planetary gearing
Abstract
A power output apparatus (100) includes an engine (102), a
double-pinion planetary gear (110), a first motor (MG1), and a
second motor (MG2). A ring gear (114), a planetary carrier (126),
and a sun gear (112) of the double-pinion planetary gear (110) are
respectively linked with a crankshaft (104) of the engine (102), a
drive shaft (108), and the first motor (MG1). The engine (102), the
second motor (MG2), the double-pinion planetary gear (110), and the
first motor (MG1) are arranged sequentially along an axis running
from the front to the rear of a vehicle. The second motor (MG2) is
required to output a greater torque than that of the first motor
(MG1) and accordingly has a larger size. The second motor (MG2) is,
however, disposed closer to the engine (102) and thereby has a
sufficient margin in the diametral direction. This configuration
reduces the size of the whole power output apparatus (100).
Inventors: |
Morisawa; Kunio (Toyota,
JP), Taga; Yutaka (Aichi-ken, JP), Nagano;
Shuji (Toyota, JP), Matsui; Hideaki (Aichi-ken,
JP) |
Assignee: |
Toyota Jidosha Kabushiki Kaisha
(Toyota, JP)
|
Family
ID: |
16942107 |
Appl.
No.: |
08/825,615 |
Filed: |
March 31, 1997 |
Foreign Application Priority Data
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Aug 13, 1996 [JP] |
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8-232614 |
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Current U.S.
Class: |
475/5; 903/903;
903/909; 903/910; 903/951; 903/906; 903/905 |
Current CPC
Class: |
B60K
6/26 (20130101); B60K 6/445 (20130101); B60W
10/26 (20130101); B60K 6/365 (20130101); B60K
6/40 (20130101); Y10S 903/909 (20130101); Y10S
903/905 (20130101); Y02T 10/62 (20130101); Y10S
903/906 (20130101); F16H 3/727 (20130101); Y10S
903/903 (20130101); Y10S 903/91 (20130101); F16H
2037/0866 (20130101); Y10S 903/951 (20130101) |
Current International
Class: |
B60K
6/04 (20060101); B60K 6/00 (20060101); F16H
3/44 (20060101); F16H 3/72 (20060101); B60K
006/00 () |
Field of
Search: |
;475/5,10 |
Foreign Patent Documents
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A 4124479 |
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Jan 1993 |
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DE |
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50-30223 |
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Mar 1975 |
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JP |
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Primary Examiner: Wright; Dirk
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
What is claimed is:
1. A power output apparatus for outputting power to a drive shaft,
said power output apparatus comprising:
an engine having an output shaft;
a first motor for transmitting and receiving power to and from a
first rotating shaft, wherein the first rotating shaft is a central
motor shaft of said first motor;
a second motor for transmitting and receiving power to and from a
second rotating shaft linked with said drive shaft; and
three shaft-type power input/output means having three shafts
respectively linked with said output shaft, said drive shaft, and
said first rotating shaft, said three shaft-type power input/output
means determining power input to and output from a residual one
shaft based on predetermined powers input to and output from any
two shafts among said three shafts;
wherein said output shaft of said engine, said drive shaft, said
first rotating shaft, and said second rotating shaft are arranged
coaxially; and
wherein said second motor is adjacent said engine, said three
shaft-type power input/output means is adjacent said second motor
and said first motor is adjacent said three shaft-type power
input/output means.
2. A power output apparatus in accordance with claim 1, said power
output apparatus further comprising a reduction gear attached to
said second rotating shaft.
3. A power output apparatus in accordance with claim 2, wherein
said reduction gear is disposed between said second motor and said
three shaft-type power input/output means.
4. A power output apparatus in accordance with claim 1, wherein
said three shaft-type power input/output means is structured as a
double-pinion planetary gear comprising a sun gear, a ring gear,
plural pairs of pinion gears, wherein said pinion gears in each
pair are linked respectively with said sun gear and said ring gear
and connected to each other, and a carrier for rotatably supporting
said plural pairs of pinion gears to be coaxial with said sun
gear,
said output shaft, said first rotating shaft, and said drive shaft
being respectively linked with said ring gear, said sun gear, and
said carrier.
5. A power output apparatus in accordance with claim 4, said power
output apparatus further comprising a reduction gear attached to
said second rotating shaft.
6. A power output apparatus in accordance with claim 5, wherein
said reduction gear is disposed between said second motor and said
three shaft-type power input/output means.
7. A power output apparatus in accordance with claim 1, wherein
said second motor has a central motor shaft, and wherein said
central motor shaft of said second motor is coaxial with said
output shaft, said drive shaft, said first rotating shaft and said
second rotating shaft.
8. A power output apparatus in accordance with claim 5, wherein
said second motor is linked with said carrier by a central motor
shaft of said second motor.
9. A power output apparatus in accordance with claim 8, wherein
said central motor shaft of said second motor is coaxial with said
output shaft, said drive shaft, said first rotating shaft and said
second rotating shaft.
10. A power output apparatus for outputting power to a drive shaft,
said power output apparatus comprising:
an engine having an output shaft;
a first motor for transmitting and receiving power to and from a
first rotating shaft;
a second motor for transmitting and receiving power to and from a
second rotating shaft linked with said drive shaft, wherein the
second rotating shaft is a central motor shaft of said second
motor;
three shaft-type power input/output means having three shafts
respectively linked with said output shaft, said drive shaft, and
said first rotating shaft, said three shaft-type power input/output
means determining power input to and output from a residual one
shaft based on predetermined powers input to and output from any
two shafts among said three shafts;
wherein said output shaft of said engine, said drive shaft, said
first rotating shaft, and said second rotating shaft are arranged
coaxially, and wherein said second motor is adjacent to said
engine, said three shaft-type power input/output means is adjacent
to said second motor, and said first motor is adjacent to said
three shaft-type power input/output means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power output apparatus, and more
specifically to a power output apparatus for outputting power to a
drive shaft.
2. Description of the Prior Art
Known power output apparatuses for carrying out torque conversion
of power output from an engine and outputting the converted power
to a drive shaft include a combination of a fluid-based torque
converter with a speed change gear. In the torque converter, an
input shaft and an output shaft of the power are not fully locked.
This causes a slip between the input shaft and the output shaft and
leads to an energy loss corresponding to the slip. The energy loss
is expressed as the product of the revolving speed difference
between the input shaft and the output shaft and the torque
transmitted to the output shaft and is consumed as heat.
In a vehicle having such a power output apparatus mounted thereon
as its power source, at the time when significantly large power is
required, for example, at the time of starting the vehicle or
running the vehicle on an upward slope at a low speed, a large
energy loss in the torque converter undesirably lowers the energy
efficiency. Even in a stationary driving state, the efficiency of
power transmission in the torque converter is not 100%, and the
fuel consumption rate in the known power output apparatus is
thereby lower than that in a manual transmission.
In order to solve such problems, the applicants have proposed a
system that does not include the fluid-based torque converter but
has an engine, a planetary gear, two motors, and a battery and
regulates the power output from the engine with the planetary gear
and the two motors, so as to output the regulated power to the
drive shaft (JAPANESE PATENT LAYING-OPEN GAZETTE No. 50-30223). In
this reference, however, there is substantially no specification
regarding the configuration of the respective constituents when the
system is installed in a limited space, such as a vehicle or a
ship.
SUMMARY OF THE INVENTION
One object of the present invention is thus to provide a power
output apparatus that can output power from an engine to a drive
shaft with a high efficiency.
Another object of the present invention is to realize an efficient
configuration of the respective constituents of a power output
apparatus installed in a limited space.
Still another object of the present invention is to reduce the size
of the whole power output apparatus.
At least part of the above and the other related objects is
realized by a power output apparatus for outputting power to a
drive shaft of the present invention, the power output apparatus
comprises: an engine having an output shaft; a first motor for
transmitting and receiving power to and from a first rotating
shaft; a second motor for transmitting and receiving power to and
from a second rotating shaft linked with the drive shaft; and three
shaft-type power input/output means having three shafts
respectively linked with the output shaft, the drive shaft, and the
first rotating shaft, the three shaft-type power input/output means
determining power input to and output from a residual one shaft
based on predetermined powers input to and output from any two
shafts among the three shafts, wherein the output shaft of the
engine, the drive shaft, the first rotating shaft, and the second
rotating shaft are arranged coaxially, the engine, the second
motor, the three shaft-type power input/output means, and the first
motor being arranged in this sequence.
In the power output apparatus of the present invention, the second
motor that is larger in size than the first motor is placed near
the engine. This configuration enhances the consistency in the
structure of the power output apparatus and allows the power output
apparatus to be readily installed in a limited space.
The power output apparatus of the present invention includes three
shaft-type power input/output means, which has three shafts
respectively linked with the output shaft of the engine, the drive
shaft, and the first rotating shaft of the first motor. When powers
are input to and output from any two shafts among these three
shafts, the three shaft-type power input/output means inputs and
outputs power, which is determined according to the input and
output powers, to and from a residual one shaft. Namely the power
input to and output from the drive shaft can be regulated by
regulating the power output from the engine and the power input to
and output from the first motor. The second motor inputs and
outputs the power to and from the drive shaft via the second
rotating shaft linked with the drive shaft. The drive shaft
accordingly receives the power input and output via the three
shaft-type power input/output means as well as the power input to
and output from the second motor.
In accordance with one aspect of the power output apparatus of the
present invention; wherein the three shaft-type power input/output
means is structured as a double-pinion planetary gear comprising a
sun gear, a ring gear, plural pairs of pinion gears, wherein the
pinion gears in each pair are linked respectively with the sun gear
and the ring gear and connected to each other, and a carrier for
rotatably supporting the plural pairs of pinion gears to be coaxial
with the sun gear; the output shaft, the first rotating shaft, and
the drive shaft being respectively linked with the ring gear, the
sun gear, and the carrier.
In accordance with another aspect of the power output apparatus of
the present invention, the power output apparatus further comprises
a reduction gear attached to the second rotating shaft. This
structure enables the reduction gear to carry out the torque
conversion of the power output from the second motor, thereby
allowing a wider range of motors to be applicable for the second
motor. In this structure, wherein the reduction gear may be
disposed between the second motor and the three shaft-type power
input/output means. In this structure, the reduction gear and the
three shaft-type power input/output means are placed adjacent to
each other. A common supply device of a lubricant can thus be used
for the operations of the reduction gear and the three shaft-type
power input/output means. This effectively reduces the size of the
whole power output apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a configuration of a power output apparatus 100
mounted on a vehicle as a first embodiment according to the present
invention;
FIG. 2 is a block diagram schematically illustrating structure of
the power output apparatus 100 of the first embodiment;
FIG. 3 shows structure of a double-pinion planetary gear 110
included in the power output apparatus 100 of the embodiment;
FIG. 4 is a nomogram showing the relationship between the revolving
speed and the torque on the three shafts linked with the
double-pinion planetary gear 110;
FIG. 5 is a nomogram showing the relationship between the revolving
speed and the torque on the three shafts linked with the
double-pinion planetary gear 110;
FIG. 6 shows a configuration of a power output apparatus 200
mounted on a vehicle as a comparative example;
FIG. 7 is a nomogram showing the relationship between the revolving
speed and the torque on the three shafts linked with a conventional
planetary gear 210 included in the power output apparatus 200 of
the comparative example;
FIG. 8 shows a configuration of a power output apparatus 300
mounted on a vehicle as a second embodiment according to the
present invention;
FIG. 9 is a block diagram schematically illustrating structure of
the power output apparatus 300 of the second embodiment; and
FIG. 10 illustrates structure of a double-pinion planetary gear 110
and a reduction gear 310 included in the power output apparatus 300
of the second embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Some modes of carrying out the present invention are described as
preferred embodiments. FIG. 1 shows a configuration of a power
output apparatus 100 mounted on a vehicle as a first embodiment
according to the present invention; FIG. 2 is a block diagram
schematically illustrating structure of the power output apparatus
100 of the first embodiment; and FIG. 3 shows structure of a
double-pinion planetary gear 110 included in the power output
apparatus 100 of the embodiment. As a matter of convenience, the
configuration of the power output apparatus 100 of the first
embodiment mounted on the vehicle is discussed with the drawing of
FIG. 1, after the explanation of the structure of the power output
apparatus 100 with the drawings of FIGS. 2 and 3.
Referring to FIGS. 2 and 3, the power output apparatus 100 of the
first embodiment mainly includes an engines 102 driven by gasoline
as a fuel, a double-pinion planetary gear 110 having a ring gear
114 mechanically linked with a crankshaft 104 of the engine 102, a
first motor MG1 connecting with a sun gear 112 of the double-pinion
planetary gear 110, a second motor MG2 connecting with a planetary
carrier 126 of the double-pinion planetary gear 110, and a
controller 150 for controlling operation of the engine 102 and
driving and regulating the first motor MG1 and the second motor
MG2.
As shown in FIGS. 2 and 3, the double-pinion planetary gear 110
includes: the sun gear 112 linked with a hollow sun gear shaft 122
which a drive shaft 108 passes through; the ring gear 114 linked
with the crankshaft 104, which is coaxial with the drive shaft 108,
via a flywheel 106, a damper 107, and a ring gear shaft 124; plural
pairs of planetary pinion gears 116 and 118 arranged between the
sun gear 112 and the ring gear 114 (each pair of planetary pinion
gears 116 and 118 is hereinafter referred to as the `double-pinion
gear 115`); and the planetary carrier 126 connecting with one end
of the drive shaft 108 to support the rotating shafts of the
double-pinion gear 115 and linked with a carrier shaft 128 via the
double-pinion gear 115. One planetary pinion gear 116 in each pair
is linked with the sun gear 112 while the other 118 is linked with
the ring gear 114. The pair of planetary pinion gears are linked
with each other to revolve around the sun gear 112 while rotating
on its axis. In this double-pinion planetary gear 110, the sun gear
shaft 122, the ring gear shaft 124, and the drive shaft 108
respectively linked with the sun gear 112, the ring gear 114, and
the planetary carrier 126 function as the input and output shafts
of the power. Determination of the power input to and output from
any two shafts among the three shafts automatically determines the
power input to and output from the residual one shaft. The details
of the input and output operations of the power to and from the
three shafts of the double-pinion planetary gear 110 will be
discussed later.
Both the first motor MG1 and the second motor MG2 are constructed
as synchronous motor-generators. The motor MG1 (MG2) includes a
rotor 132 (142) having a plurality of permanent magnets 135 (145)
mounted on the circumferential face thereof and a stator 133 (143)
on which three-phase coils 134 (144) generating a revolving
magnetic field are wound. The rotor 132 of the first motor MG1 is
connected to the sun gear shaft 122 linked with the sun gear 112 of
the double-pinion planetary gear 110, whereas the rotor 142 of the
second motor MG2 is connected to the carrier shaft 128 linked with
the planetary carrier 126 of the double-pinion planetary gear
110.
Although details of the controller 150 are not illustrated, the
controller 150 includes two inverter circuits for generating
electric currents of quasi-sine waves supplied to the three-phase
coils 134 and 144 of the first motor MG1 and the second motor MG2,
a battery charged and discharged via the two inverter circuits, a
motor control CPU for controlling the switching operations of the
two inverter circuits, and an engine control CPU for controlling
the operation of the engine 102. The controller 150 receives a
variety of signals output from various sensors for measuring the
conditions of the first motor MG1, the second motor MG2, and the
engine 102, and controls the operations of the first motor MG1, the
second motor MG2, and the engine 102 based on these input signals.
The control procedure carried out by the controller 150 is not
essential for the principle of the present invention and is not
specifically discussed here.
The power output apparatus 100 of the first embodiment thus
constructed is mounted on a vehicle according to the configuration
shown in FIG. 1. Referring to FIG. 1, the engine 102, the second
motor MG2, the double-pinion planetary gear 110, and the first
motor MG1 included in the power output apparatus 100 are arranged
in this sequence along the axis running from the front to the rear
of the vehicle. In the drawing of FIG. 1, only the upper half
around the crankshaft 104 and the drive shaft 108 is illustrated,
since the lower half is a mirror symmetry. A casing 101 in which
the second motor MG2, the double-pinion planetary gear 110, and the
first motor MG1 is received represents a general space for
receiving a fluid-based torque converter and a transmission in a
conventional FR-type vehicle. The power output apparatus receivable
by the casing 101 can thus be mounted on the conventional vehicle,
in place of the torque converter and the transmission. The sizes of
the first motor MG1 and the second motor MG2 and their
configuration determine whether or not the power output apparatus
100 of the first embodiment is receivable in the fixed space. The
sizes of the first motor MG1 and the second motor MG2 depend upon
the required performances as the motor or the generator. The degree
of freedom of the configuration depends upon the linkage of the
double-pinion planetary gear 110 with the three shafts, that is,
the sun gear shaft 122, the ring gear shaft 124, and the drive
shaft 108. The following describes first the performances required
for the first motor MG1 and the second motor MG2 with the
operations of the power output apparatus 100 including the
double-pinion planetary gear 110 and then the configuration of the
first motor MG1 and the second motor MG2.
The power output apparatus 100 of the first embodiment works in the
following manner. It is assumed that the engine 102 is driven at a
driving point P1 defined by a revolving speed Ne and a torque Te
and that the drive shaft 108 is driven at a driving point P2
defined by a revolving speed Nd and a torque Td, which are
respectively different from the revolving speed Ne and the torque
Te but give an identical energy to an energy Pe output from the
engine 102. Namely the power output from the engine 102 is
subjected to a torque conversion before being applied to the drive
shaft 108.
According to the mechanics, the relationship between the revolving
speed and the torque on the three shafts in the double-pinion
planetary gear 110 (that is, the sun gear shaft 122, the ring gear
shaft 124, and the drive shaft 108) can be expressed as nomograms
illustrated in FIGS. 4 and 5 and solved geometrically. The
relationship between the revolving speed and the torque on the
three shafts in the double-pinion planetary gear 110 may be
analyzed numerically through calculation of energies of the
respective shafts, without using the nomograms. For the clarity of
explanation, however, the nomograms are used in this
embodiment.
In the nomogram of FIG. 4, the revolving speed of the three shafts
is plotted as ordinate and the positional ratio of the coordinate
axes of the three shafts as abscissa. When coordinate axes S and R
respectively represent the sun gear shaft 122 and the ring gear
shaft 124, a coordinate axis C of the drive shaft 108 is given as
an exterior division of the axes S and R at the ratio of 1 to
.rho., where
.rho. represents a ratio of the number of teeth of the sun gear 112
to that of the ring gear 114 and expressed as Equation (1) given
below:
As mentioned above, the engine 102 is driven at the revolving speed
Ne, while the drive shaft 108 is driven at the revolving speed Nd.
The revolving speed Ne of the engine 102 can thus be plotted on the
coordinate axis R of the ring gear shaft 124 linked with the
crankshaft 104 of the engine 102, and the revolving speed Nd on the
coordinate axis C of the drive shaft 108. A straight line passing
through both the points is drawn, and a revolving speed Ns of the
sun gear shaft 122 is then given as the intersection of this
straight line and the coordinate axis S. This straight line is
hereinafter referred to as a dynamic collinear line. The revolving
speed Ns of the sun gear shaft 122 can be calculated from the
revolving speed Ne of the engine 102 and the revolving speed Nd of
the drive shaft 108 according to a proportional equation given as
Equation (2) below. In the double-pinion planetary gear 110, the
determination of the rotations of the two gears among the sun gear
112, the ring gear 114, and the planetary carrier 126 results in
automatically setting the rotation of the residual one gear.
The torque Te of the engine 102 is then applied upward (in the
drawing) to the dynamic collinear line on the coordinate axis R of
the ring gear shaft 124 functioning as a line of action. The
dynamic collinear line against the torque can be regarded as a
rigid body to which a force is applied as a vector. Based on the
technique of dividing the force into different lines of action
having the same direction, the torque Te acting on the coordinate
axis R is divided into a torque Tes on the coordinate axis S and a
torque Tee on the coordinate axis C. The magnitudes of the torques
Tes and Tee are defined by Equations (3) and (4) below:
The equilibrium of forces on the dynamic collinear line is
essential for the stable state of the dynamic collinear line. In
accordance with a concrete procedure, a torque Tm1 having the same
magnitude as but the opposite direction to the torque Tes is
applied to the coordinate axis S, whereas a torque Tm2 having the
same magnitude as but the opposite direction to a resultant force
of the torque Tee and the torque that has the same magnitude as but
the opposite direction to the torque Td output to the drive shaft
108 is applied to the coordinate axis C. The torque Tm1 is given by
the first motor MG1, and the torque Tm2 by the second motor MG2
having the rotor 142 attached to the carrier shaft 128. The first
motor MG1 applies the torque Tm1 in reverse of its rotation and
thereby works as a generator to regenerate an electrical energy
Pm1, which is expressed as the product of the torque Tm1 and the
revolving speed Ns, from the sun gear shaft 122. The second motor
MG2 applies the torque Tm2 in the direction of its rotation and
thereby works as a motor to output an electrical energy Pm2, which
is expressed as the product of the torque Tm2 and the revolving
speed Nd, as a power to the drive shaft 108 via the carrier shaft
128 and the planetary carrier 126.
In case that the electrical energy Pm1 is identical with the
electrical energy Pm2, all the electric power consumed by the
second motor MG2 can be regenerated and supplied by the first motor
MG1. In order to attain such a state, all the input energy should
be output; that is, the energy Pe output from the engine 102 should
be equal to an energy Pd output to the drive shaft 108. Namely the
energy Pe expressed as the product of the torque Te and the
revolving speed Ne is made equal to the energy Pd expressed as the
product of the torque Td and the revolving speed Nd.
Although the revolving speed Ns of the sun gear shaft 122 is
positive in the nomogram of FIG. 4, it may be negative according to
the revolving speed Ne of the engine 102 and the revolving speed Nd
of the drive shaft 108 as shown in the nomogram of FIG. 5. In the
latter case, the first motor MG1 applies the torque in the
direction of its rotation and thereby works as a motor to consume
the electrical energy Pm1 given as the product of the torque Tm1
and the revolving speed Ns. The second motor MG2, on the other
hand, applies the torque in reverse of its rotation and thereby
works as a generator to regenerate the electrical energy Pm2, which
is given as the product of the torque Tm2 and the revolving speed
Nd, from the carrier shaft 128. In case that the electrical energy
Pm1 consumed by the first motor MG1 is made equal to the electrical
energy Pm2 regenerated by the second motor MG2 under such
conditions, all the electric power consumed by the first motor MG1
can be supplied by the second motor MG2.
The above description refers to the fundamental operation, in which
all the power output from the engine 102 is subjected to the torque
conversion and output to the drive shaft 108. The power output
apparatus 100 of the embodiment can carry out another operation, in
which the sum of the power output from the engine 102 and the power
based on the electric power discharged from the battery (not shown)
included in the controller 150 is output to the drive shaft 108.
This operation is realized by setting the torque Tm2 of the second
motor MG2 to be greater than the calculated torque (Td-Tee)
discussed in FIGS. 4 and 5. This operation enables the power
greater than the output power of the engine 102 to be output to the
drive shaft 108. A small-sized engine that can output only the
power less than the required power is thus applicable for the
engine 102. In this case, the performance of the engine 102 is
determined by choosing a best combination of the performances of
the second motor MG2 and the battery, which attains the highest
possible efficiency.
The power output apparatus 100 of the embodiment can also carry out
still another operation, in which only the power based on the
electric power discharged from the battery is output to the drive
shaft 108 while the engine 102 is at a stop. The second motor MG2
directly outputs the power to the drive shaft 108 via the carrier
shaft 128 and the planetary carrier 126, in order to realize this
operation. In this case, the torque Tm1 of the first motor MG1 is
equal to one. This operation enables a drive causing substantially
no pollution in areas requiring the stricter environmental
protection.
The power output apparatus 100 of the first embodiment can also
carry out a variety of other operations. For example, part of the
power output from the engine 102 is subjected to the torque
conversion and output to the drive shaft 108 while the residual
power is regenerated by either the first motor MG1 or the second
motor MG2 and used to charge the battery. As another example, all
the power output from the engine 102 is regenerated by the first
motor MG1 and used to charge the battery while the second motor MG2
keeps the carrier shaft 128 in the locked state. As still another
example, the first motor MG1 cranks the engine 102 while the second
motor MG2 keeps the carrier shaft 128 in the locked state.
As clearly understood from the description of these various
operations, the second motor MG2 is required to have the
performance that can drive the vehicle by itself. The second motor
MG2 is accordingly greater in size than the first motor MG1, which
is required to have the performance that can ensure the balance on
the dynamic collinear line and crank the engine 102. The torque
output from the motor is proportional to the axial length of the
motor as well as to the second power of the diameter of the motor.
It is thus preferable that the second motor MG2 is arranged in a
place that has a margin in the diametral direction.
The following describes the configuration of the first motor MG1
and the second motor MG2. In case that the double-pinion planetary
gear 110 is used as the three shaft-type power input/output means
like the power output apparatus 100 of the embodiment, it is
desirable that the ring gear shaft 124 connecting with the ring
gear 114 is linked with the crankshaft 104 of the engine 102. This
is ascribed to the actions on the dynamic collinear lines discussed
in FIGS. 4 and 5 as well as to the fact that the power output from
the power output apparatus 100 to the drive shaft 108 is mainly
generated by the engine 102 and that the engine 102 can not rotate
in a reverse direction. When it is assumed that the drive shaft
108, the sun gear shaft 122, the ring gear shaft 124, and the
carrier shaft 128 are all coaxial, one possible configuration is
the arrangement of the engine 102, the second motor MG2, the
double-pinion planetary gear 110, and the first motor MG1 in this
sequence, like the power output apparatus 100 of the first
embodiment. Other possible configurations include an arrangement of
the engine 102, the double-pinion planetary gear 110, the second
motor MG2, and the first motor MG1 in this sequence and another
arrangement of the engine 102, the second motor MG2, the first
motor MG1, and the double-pinion planetary gear 110 in this
sequence. The configuration of the power output apparatus 100 of
the embodiment shown in FIG. 1, in which the engine 102, the second
motor MG2, the double-pinion planetary gear 110, and the first
motor MG1 are arranged in this sequence, is advantageous among the
possible configurations by taking into account the performance of
the second motor MG2 and the shape of the casing 101.
In a power output apparatus 200 of FIG. 6 given as a comparative
example, a conventional planetary gear 210 having only one
planetary pinion gear interposed between the sun gear and the ring
gear is used as the three shaft-type power input/output means. FIG.
7 is a nomogram showing the operation of this conventional
planetary gear 210. When a coordinate axis S of a sun gear shaft
222 and a coordinate axis R of the drive shaft 108 are positioned
on either ends of a line segment, a coordinate axis C of a carrier
shaft 228 connecting with a planetary carrier 226 is given as an
interior division of the axes S and R at the ratio of 1 to .rho..
In this case, it is desirable that the carrier shaft 228 is linked
with the crankshaft 104 of the engine 102. When it is assumed that
the drive shaft 108, the sun gear shaft 222, and the carrier shaft
228 are all coaxial, possible configurations include an arrangement
of the engine 102, a motor MG3 corresponding to the first motor
MG1, the planetary gear 210, a motor MG4 corresponding to the
second motor MG2 in this sequence like the power output apparatus
200 of the comparative example shown in FIG. 6, another arrangement
of the engine 102, the planetary gear 210, the motor MG3, and the
motor MG4 in this sequence, and still another arrangement of the
engine 102, the motor MG3, the motor MG4, and the planetary gear
210 in this sequence. In the structure of the comparative example
using the conventional planetary gear 210, the motor MG4
corresponding to the larger-sized second motor MG2 is placed in a
rear portion of the vehicle. A casing 201 is thus required to have
a larger space in the rear portion than that of the casing 101. For
the comparison, the gear ratio of the planetary gear 210 of the
comparative example is set to be identical with the gear ratio of
the double-pinion planetary gear 110 of the first embodiment.
The above description proves that the structure of the power output
apparatus 100 of the first embodiment, that is, the application of
the double-pinion planetary gear 110 as the three shaft-type power
input/output means and the configuration of the engine 102, the
second motor MG2, the double-pinion planetary gear 110, and the
first motor MG1 in this sequence, is advantageous.
The power output apparatus 100 of the first embodiment includes the
double-pinion planetary gear 110 as the three shaft-type power
input/output means. This structure enables the larger-sized second
motor MG2, which is required to output a larger torque among the
two motors MG1 and MG2, to be arranged in the place that is closer
to the engine 102 and thereby has a sufficient margin in the
diametral direction. This enhances the consistency of the
configuration in the power output apparatus 100 and enables the
power output apparatus 100 to be readily mounted on the vehicle.
The power output apparatus 100 can be received in a general space,
in which the fluid-based torque converter and the transmission are
received in the conventional FR-type vehicle. The power output
apparatus 100 of the embodiment can thus be mounted on the vehicle
without any modification of the design of the space.
In the power output apparatus 100 of the first embodiment,
permanent magnet (PM)-type synchronous motors are used as the first
motor MG1 and the second motor MG2. Any other motors which can
implement both the regenerative operation and the power operation,
such as variable reluctance (VR)-type synchronous motors, vernier
motors, d.c. motors, induction motors, superconducting motors, and
stepping motors, may, however, be used according to the
requirements.
Another power output apparatus 300 is described as a second
embodiment according to the present invention. FIG. 8 shows a
configuration of the power output apparatus 300 of the second
embodiment mounted on a vehicle; FIG. 9 is a block diagram
schematically illustrating structure of the power output apparatus
300 of the second embodiment; and FIG. 10 illustrates structure of
a double-pinion planetary gear 110 and a reduction gear 310
included in the power output apparatus 300 of the second
embodiment. The power output apparatus 300 of the second embodiment
has a similar structure to that of the power output apparatus 100
of the first embodiment, except that the power output apparatus 300
includes the reduction gear 310 and a motor MG5 in place of the
second motor MG2. The same constituents in the power output
apparatus 300 of the second embodiment as those in the power output
apparatus 100 of the first embodiment are shown by like numerals
and symbols and not specifically described here.
The reduction gear 310 included in the power output apparatus 300
of the second embodiment is structured as a planetary gear
including a sun gear 312, a ring gear 314, and a planetary pinion
gear 316 as shown in FIG. 10. A sun gear shaft 322 fixes the sun
gear 312 in the reduction gear 310 to the casing 101 not to allow a
rotation of the sun gear 312. The planetary pinion gear 316 in the
reduction gear 310 is linked with the carrier shaft 128, which is
connected to the planetary carrier 126 via the double-pinion gear
115 of the double-pinion planetary gear 110. The ring gear 314 in
the reduction gear 310 is linked with a rotor 342 of the motor MG5
by a ring gear shaft 324. When the gear ratio of the reduction gear
310 constructed as the planetary gear is equal to .rho. (=number of
teeth of the sun gear/number of teeth of the ring gear), the
rotation of the motor MG5 is output as the rotation of 1/(1+.rho.)
to the carrier shaft 128. The torque output from the motor MG5 is
accordingly output as the (1+.rho.)-fold torque to the carrier
shaft 128. The required size for the motor MG5 is accordingly
smaller than that for the second motor MG2 in the first embodiment.
For example, the motor MG5 has a less axial length for the same
diameter. The structure of the second embodiment including the
reduction gear 310 can thus be received in the casing 101 of the
first embodiment.
The power output apparatus 300 of the second embodiment includes
the reduction gear 310 disposed between the motor MG5 and the
double-pinion planetary gear 110. This structure reduces the size
of the motor MG5. The degree of freedom of selection for the motor
MG5 can be increased by adjusting the gear ratio of the reduction
gear 310. In the power output apparatus 300 of the second
embodiment, the reduction gear 310 is placed adjacent to the
double-pinion planetary gear 110, so that a common supply device of
a lubricant can be used for the reduction gear 310 and the
double-pinion planetary gear 110. This structure reduces the size
of the whole power output apparatus 300. The power output apparatus
300 of the second embodiment exerts the same effects as those of
the power output apparatus 100 of the first embodiment.
The present invention is not restricted to the above embodiments,
but there may be many modifications, changes, and alterations
without departing from the scope or spirit of the main
characteristics of the present invention.
It should be clearly understood that the above embodiments are only
illustrative and not restrictive in any sense. The scope and spirit
of the present invention are limited only by the terms of the
appended claims.
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